There has been known an image reading apparatus configured to drive a feeding device which feeds a sheet of document to a reading unit such as CIS and a moving device, for example a carriage, which moves the reading unit, with power from one motor (for example, refer to JP-A-2006-86817). According to the image reading apparatus, a position of a switching gear which is a transmission unit for transmitting driving power of the motor is switched between a feeding unit-side position where the switching gear transmits the power to the feeding device and a carriage-side position where the switching gear transmits the power to the moving device. Thereby, it is possible to drive the feeding device and the moving device by one motor.